1. Field of the Invention
The invention relates to a flat energy cable with at least one core and with at least one sheath accommodating the core.
2. Description of the Related Art
The purpose of such flat cables is to carry at least one core—comprising an electric conductor insulated by an insulating layer—, and, optionally, telecommunication conductor/s—such as optical fiber/s—and/or fluid duct/s—for example for transporting oil, water or gas—from supply equipment to a device, for example a movable machine. In the following of the present description, the optional telecommunication conductor/s and fluid duct/s could be collectively referred to as “lines”.
The flat energy cable is provided with a sheath protecting the at least one core and the optional lines from external influences. In moving devices, especially designed to execute movements over a large area, the flat cable is divided into an upper upper length portion and a lower length portion. The lower length portion lies in a distribution trough on a distribution surface whilst the upper length portion that is connected with the lower length portion by means of a bent section. In this there is the advantage, compared to a cable guide in a power supply chain, that such flat cable device is easier and cheaper to manufacture. However, a flat cable does not have the same stability as a power supply chain and therefore is not as resistant to wear. Furthermore, there is the disadvantage that, in comparison to a power supply chain, in view of the flexibility of the cable an excessive bending at the bent section can occur, challenging the cable integrity and possibly causing the sliding of the two longitudinal section one in touch with the other, causing further damages by friction.
It is, therefore, a problem faced by the invention to develop a flat energy cable in such a manner that it has an improved stability and resistance to wear.
Another problem to be considered is that of push and pull forces exerted, sometimes abruptly, by the moving device. These forces can challenge the integrity of the cable and reduce the work-life thereof. In the case of pushing forces, a specific phenomenon called “buckling” can occur.
US 2007/0144376 relates to a device for guiding at least one line that protects it, in the distribution trough, in such a manner that it is guided at least partially without contact. The cable is enclosed by a sheath, on the lower side of which, facing the distribution surface, a lower-side magnet is disposed. Facing the lower-side magnet, a distribution-surface magnet is disposed on the distribution surface. As a result, the sheath, with the cable enclosed in it, is held suspended above the distribution surface.
The cable is guided by a device bearing magnets. No hint is provided about the push/pull forces exerted on the cable and to remedy to the problems therefrom.
U.S. Pat. No. 6,405,843 relates to a self supporting electrical cable, especially of use in linear motion devices. The cable is in the form of a band having a crowned or curved cross-section. The band is self supporting and is typically employed in a looped configuration. The band is composed of a Mylar or other plastic or electrically insulating laminate with electrical conductors and reinforcing elements. The reinforcing elements are typically stainless steel. In use the cable is usually folded back on itself 180° to provide a loop configuration with a fixed radius loop end in which the loop is moveable along the direction of travel.
The cable does not comprise magnetic parts. The self-support feature is provided by a curved configuration of the cable surface and by the band on the cable surface. No hint is provided about the push/pull challenging forces exerted on the cable.
U.S. Pat. No. 6,215,068 relates to a line guiding assembly. The line bundling means has disposed on its outside a sliding means with good slidability. The sliding means prevents friction between an upper length portion and a lower length portion of a line assembly. The line bundling means may comprise line clamps spaced apart in the longitudinal direction of the line assembly, with the sliding means being disposed on the outside of said line clamps. The sliding means consist of a flexurally elastic material, such as steel, or a slidable plastic material, such as polyurethane, polyamide, and polytetrafluoroethylene. The sliding means then does not only form a mechanical sliding protection for the cable jacket, but is adapted to keep the tensile and thrust forces, exerted during reciprocation of the movable means, away from the line assembly. When the longitudinal ends of the sliding means are attached in such a manner to the stationary and the movable means, respectively, a strain relief for the line assembly is also established. The assembly does not comprise magnetic parts. The cable of the assembly does not have specific reinforcing elements for protecting the cable against pull and push forces exerted thereupon.
JP 06-078439 relates to a power supply device to a movable part, where a permanent magnet is provided on the side of the movable part so as to prevent the meandering of a flat cable. The cable assembly, moving in a guide case provided with a permanent magnet plate, comprises a flat cable and a magnetic plate positioned onto the cable surface internal to the loop. Optionally, a tape shape guide (a resin tape) is provided onto the cable surface facing the guiding case for lowering the friction.
The cable is moved in a guiding device. The magnet provided to the cable operates with the permanent magnet of the guiding device. No hint is provided about the push/pull forces exerted on the cable and to remedy to the problem therefrom.